SW4201 / SW4601 / SW4221 / SW4661

SW series impedance tube is designed base on transfer-function method, according to GB/T 18696.2, GB/J 88, ISO 10534-2, ASTM E1050-12, and ASTM E2611-17 standards, including impedance tube kit (SW4201 / SW4601) and transmission loss tube kit (SW4221 / SW4661).

SW series impedance tube is based on two-microphone transfer-function method. The normal incidence sound absorption coefficients and specific acoustic impedance ratios of materials in the full measurement frequency range can be obtained only by one test. Compared with the tube designed based on the standing wave ratio method, it significantly improves the test efficiency of material acoustic properties. And the transmission loss tube is based on four-microphone transfer-function method. The transmission loss of materials to be measured can be obtained by measuring the sound pressure level at four fixed positions in tube with two different terminations and calculating a complex transfer function.

The inner diameter of SW series impedance tube is 100 mm (SW4201 / SW4221, test frequency range is 50 Hz~1.6 kHz) and 29 mm (SW4601 / SW4661, test frequency range is 500 Hz~6.4 kHz). The two types of impedance tubes can be used together to broaden the test frequency range.

SW series impedance tube is made of hard aluminum alloy, with compact design, light weight and easy to assemble, which is convenient for filed measurement of acoustic properties of materials.


    ●  Acoustical properties of material measurements based on the transfer-function method according to absorption coefficient standard of GB/T 18696.2, GB/J 88, ISO 10534-2 and ASTM E1050-12, and transmission loss standard of ASTM E2611–17

    ●  Separable sample holder tube is convenient for placement of materials to be test
    ●  Faster and more accurate compared to the standing wave ratio method
    ●  Frequency range can cover high and low bands, depends on various diameter of tube and the different microphone spacing
    ●  Improved sealing and connecting structures between tubes are convenient for measurement and has much better sealing and sound insulation performance



    ●  Quantitative measurement of acoustic properties of materials

    ●  Measure the acoustic coefficients of materials which required for simulation software

Impedance Tube/Transmission Loss Tube







GB/T 18696.2, GB/J 88ISO 10534-2, ASTM E1050-12

ASTM E2611-17

Frequency Range

50 Hz~1.6 kHz

500 Hz~6.4 kHz

50 Hz~1.6 kHz

500 Hz~6.4 kHz


100 mm

29 mm

100 mm

29 mm

Length of Tube1

893 mm

603 mm

1261 mm

781 mm

Zero Absorption

50 Hz~4 kHz: <5 %, 5 kHz~6.4 kHz: <10 %

(calculated in 1/3-octave band)

Operating Environment

Temperature: -10 °C~50 °C, Humidity: 5 %RH~95 %RH (non-condensing)

Note 1: The length is the minimum combination state.


Rated Impedance

4 Ω




89.8 dB (2.83 V@1 m)

Rated Power

10 W (continuous)

Peak Power

30 W (short duration: duty cycle 1/3, on time 50 s)

Audio Interface

Banana socket

Measurement Microphone


MPA416 Prepolarization Microphone



Sensitivity (±2 dB)

50 mV/Pa (-26 dB re 1 V/Pa)

Output Impedance

< 110 Ω

Dynamic Range

29 dBA ~ 127 dB

Self-generated Noise

29 dBA

Power Supply


Download information:

SW4201/4601 Impedance Tube Kit,SW4221/4661 Transmission Loss Tube Kit